Introduction: Characterizing cerebral autoregulation has been an ongoing challenge in traumatic brain injury (TBI) and aneurysmal subarachnoid hemorrhage(SAH). With new technologies available for continuous monitoring, there has been interest to correlate this information with outcome and to develop an algorithm for clinical management.
Methods: Thirty-three SAH patients and 31 patients with TBI, i.e., Glasgow Coma Scale less than 8, were included in this study. Each patient had intracerebral monitoring via the Hummingbird SynergyDuo(Innerspace) bolt system with continuous capture of data via the CNS system(Component Neuromonitoring System, CNS Technologies LLC) for at least 5 days. Intracranial data captured include ventricular intracranial pressure (ICP), parenchymal ICP, focal brain tissue oxygenation( tO2) (Licox, Integra) and thermodilution cerebral blood flow(CBF) (Bowman Perfusion, Hemedex); systemic variables are also continuously captured. The oxygen and perfusion probes have a fixed spatial relationship between them, with placement into the deep frontal white matter adjacent to the ventriculostomy. We define a new set of indices dOx, dPx, and dICPx to examine the dynamics between focal measurements of tO2 and CBF and global ICP.
Results: Use of the Hummingbird system has provided a consistent data acquisition which is automatically captured via the CNS system. Dynamic analysis of individual data streams indicates that despite a spatially fixed relationship between CBF and tO2 there is not necessarily a correlation between the two except in clinical extremis. However, ICP responsiveness to changes in blood pressure mirrored a similar responsiveness by CBF to changes in blood pressure which we did not observe in changes in tO2.
Conclusions: The fixed positions between monitors for ICP, CBF and tO2 provides reliable access to physiological information that warrants further examination. Preliminary data suggests a weaker correlation between tO2 and the other variables-- CBF, ICP and blood pressure, with stronger differential responses of CBF and ICP.
Patient Care: The two large patient populations that have the potential for secondary injury may directly benefit as we begin to identify a more algorithmic approach toward minimizing further injury.
Learning Objectives: By the conclusion of this session, participants should be able to: 1) Describe the understand available monitoring technologies 2) Discuss issues that are challenging in management of severe traumatic brain injury and aneurysmal subarachnoid hemorrhage and how monitoring may be useful 3. Identify how to incorporate treatment strategies into their own clinical practice